On the basis of a lock cylinder according to the prior art (Swiss Patent No. 449,445) and U.S. Pat. No. 3,412,588 with mechanical tumblers, for blocking or freeing the relative movement between rotor and stator, an object of the present invention is to so further develop a lock cylinder of the aforementioned type that it can be operated electronically or mechanically or in combined form in a lock system through an electrically controllable tumbler.